<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Loading</title>
  <style>
    body {
      display: flex;
      justify-content: center;
      align-items: center;
      min-height: 100vh;
    }

    @keyframes rotate {
      to {
        transform: rotate(1turn)
      }
    }

    .loading {
      max-width: 50%;
      line-height: 1.4;
      font-size: 1.2rem;
      font-weight: bold;
      text-align: center;
    }

    .loading__author {
      font-weight: normal;
      font-size: 0.9rem;
      color: rgba(189, 189, 189, 1);
      margin: 0.6rem 0 2rem 0;
      display: block;
    }

    .loading__anim {
      width: 35px;
      height: 35px;
      display: inline-block;
      border: 5px solid rgba(189, 189, 189, 0.25);
      border-left-color: rgba(3, 155, 229, 1);
      border-top-color: rgba(3, 155, 229, 1);
      border-radius: 50%;
      animation: rotate 600ms infinite linear;
    }
  </style>
</head>

<body>
  <section class="loading">
    For new sidebar colors, click your workspace name, then Preferences > Sidebar > Theme
    <span class="loading__author"> - Your friends at Slack</span>
    <span class="loading__anim"></span>
  </section>
</body>

</html>